Анотация: Oviposition patterns of engorged adult females of dog ticks: Rhipicephalus sanguineus and Haemaphysalis leachi leachi were studied at various photoperiods under constant temperature and relative humidity in the laboratory. The ticks were subjected to six different photoperiods throughout the period of oviposition and eggs were removed six hours. There were no significant differences in the mean pre-oviposition period, duration of oviposition and the number of eggs laid by R. sanguineus and H. leachi leachi in all the photoperiodic conditions. The pre-oviposition periods of R. sanguineus and H. leachi leachi sampled every six hours (disturbed group) were significantly lower (p<0.05) than those sampled every 24 hours (undisturbed group). No significant differences existed in the duration of oviposition of the disturbed (8.0+-1.78 and 8.0 +-1.11) and undisturbed (8.6+-1.79 and 8.9+-0.23) groups. Also no significant difference occurred in the number of eggs laid per mg body weight of the disturbed and undisturbed groups for R. sanguineus and H. leachi leachi respectively. Oviposition started during the scotophase in all the experimental ticks and egg collection started at 24 hours. The oviposition patterns under continuous darkness for 24 hours and continuous light for 24 hours were characterised by fluctuating peaks of egg-laying which did not follow any obvious pattern or rhythm while in other photoperiodic conditions there were peaks of oviposition with more obvious frequency patterns for both species. No significant differences were observed in the mean total number of eggs laid at the photophase and scotophase in less than 12 hours of light and 12 hours of darkness and vica versa. However, more eggs were laid at the scotophase than at the photophase by R. sanguineus and H. leachi leachi respectively. Engorged adult females of R. sanguineus and H. leachi leachi laid more eggs during scotophase than during photophase respectively, suggesting that both species exhibited ovipositional rhythm