This Sedentary behaviour (SB) affects health and performance in highly trained athletes. A number of research efforts have demonstrated that physical inactivity and SB are two independent entities. However, SB in highly trained athletes in Saudi Arabia has not been studied. Therefore, the aim of this study was to assess SB in Saudi basketball players. Sixteen basketball players (mean ± Standard Deviation (SD), age, 22.6 ± 3.3 years; body mass, 77.8 ± 10.5 kg; height, 182.9 ± 10.8 cm) participated in this study. A self-report SB questionnaire was used to assess time spent on watching television, using a computer/Internet, playing electronic games; total sedentary time; and sleep duration. The cut-off point of ≥2 h/day was used to categorise the outcome. Inadequate sleep duration was defined as <7 (h/night). The results show that 93.7% of basketball payers spent more than 2 h/day in sedentary activities. On average, the total amount of time spent on sedentary activities was 455 ± 218 min/day. Computer/Internet use was the predominant SB (191.8 ± 115.8 min/day) among basketball players, followed by electronic games playing (186.2 ± 113.9 min/day). The mean (±SD) sleep duration for weekdays and weekends were 7.2 ± 1.5 and 7.8 ± 1.6 (h/night), respectively. The weekday and weekend sleep duration analysis also shows that 25% and 12.5% of basketball players had insufficient sleep (<7 h/night) during weekdays and weekends, respectively. These findings indicate that athletes spent significant amounts of time in SB. This may suggest that SB still exists in highly trained athletic people. A quarter of the basketball players had an inadequate weekday sleep duration, and this short weekday sleep was compensated for during the weekend.