A variety of lasers can be used for laser-assisted hair removal. These range from shorter-wavelength lasers like ruby (694 nm) to longer wavelengths like Nd:YAG (1,064 nm). The target chromophore for all these laser systems is follicular melanin. Melanin content in both hair and epidermis varies widely across skin types. In darker skin types, there is an increased risk of epidermal damage due to absorption of energy by the melanin in epidermis. This increased epidermal melanin also reduces the energy absorption by follicular melanin. This energy absorption may be reduced by using lasers with longer wavelengths like the Nd:YAG laser. The aim of this study is to evaluate the effect of increasing the pulse duration using different fluences on the efficacy of long-pulsed Nd-YAG laser in impairment of hair regrowth. Thirty female patients with hirsutism were involved in this prospective clinical trial (80% of them with skin type IV and 20% with skin type III). The chin area of each patient was divided into three areas. Area (A) as the control area at the right side of the patient was treated by the classic parameters of the device. Areas (B) & (C) at the left side of the same patient received higher pulse duration while area C received high fluence. The treatment sessions were performed at one month interval for four consecutive months. Clinical evaluation and follow up were done every two weeks. In our study the face side which was treated by a pulse duration of 50 msec, fluence 40 J/cm (left A) achieved marked improvement regarding hair reduction count in 45.83% of the patients. Yet there was no statistically significant difference between this side and the others (right side, left side B). At the end of the study (after four laser sessions) the average mean of hair reduction was 68.5375 % which indicates the efficacy of long pulsed Nd:YAG laser in hair removal. Both together (image analysis and the modified trichogram) showed more hair impairment with longer pulse duration on the left side. Our conclusion is that the use of long pulsed Nd:YAG can be considered as a safe and effective device for hair removal. Increasing the pulse duration significantly decreases the hair thickness and inducing telogen in the treated hairs but not the hair count. We therefore recommended that increasing the pulse duration is one of the important manipulations in the parameters required to increase the efficacy of longer hair depilation.