On-street Parking activities on the curb of streets can disrupt the traffic flow and cause traffic congestion. This study aimed to examine the effect of On-street Parking on vehicle velocity and Level of Service (LO). This research was conducted on Cik Di Tiro Street, around Panti Rapih Hospital, Yogyakarta. The analysis of road segmentation was guided by the Indonesian highway capacity manual (1997). The analysis results revealed that during weekdays, the vehicle velocity in the morning without any On-Street Parking was 29.45 kilometers per hour, while the level of service was at level C, meanwhile, in the afternoon, and in the evening, the vehicle velocity was 21,672 kilometers per hour with the parking accumulation as many as 1-2 light vehicles, 4-18 motorcycles, and the level of service was at level E. Meanwhile, in the weekend, the vehicle velocity in the morning without On-street Parking was 29.16 kilometers per hour, and the level of service was at level A. Meanwhile, in the afternoon and evening, the vehicle speed was 23.04 kilometers per hour, with the parking accumulation as many as 1-3 light vehicles, 1-14 motorycles, and the level of services were at Level D and C in the afternoon.