Data were collected in two consecutive years (1990, 1991) and included 19000, 27158 and 18999 records of three different periods of simulated cumulated 31 – 120 (CMRS₁), 61 – 150 (CMRS₂) and 31 – 150 (CMRS₃) day of lactation for the first lactation in Fleckvieh cows from the Official Federation of Austrian Cattle Breeders (ZAR).    Yields of 305-day (305-d MY) and cumulative milk (CMY), fat (305-d FY & CFY), protein (305-d PY & CPY), fat-plus-protein (305-d FPY & CFPY) and percentage of protein yield/fat yield (305 POF & CPOF%) under CMRS₁ up to CMRS₃ were studied.  The effects of calving year-season (CYS), age at first calving (AFC), days open (DO), the time from the first monthly test-day to next calving date (TFTNC) and sire on 305-day and cumulative milk traits (305-day MYT & CMYT) were examined under various cumulative monthly recording systems (CMRS). In general, the estimates of coefficient of variation (C.V) for 305-day MYT were (16.5 – 18.6%) lower than the calculated CMYT (20.4 – 22.9%), which reflected the large for CMYT.   The estimates of C.V. for both FY and CFY were higher than all other 305-day MYT and CMYT.  On the other side, the estimates of C.V. for both POF% and CPOF% under CMRS seemed to be similar. The effects of sire were highly significant (P < 0.001) for all traits studied.  Consequently, sire selection would lead to genetic improvement of milk traits.  Calving year-season (CYS) affected significantly (P < 0.001) most of the studied traits under CMRS.  Days open, age at first calving and the time from the first monthly test day to next calving date affected, significantly (P < 0.05 or P < 0.01 or P < 0.001) all traits studied and should be considered in sire and cow evaluation program.