Abstract: Data on male-infant social behavior of Macaca thibetana were collected in a period from January to September 1997,covering the whole birth season and the early mating season.One-minute point sampling was used for male-infant caretaking (in lap+in proximity),and five-minute event sampling for male-infant-male interactions (triads).The observation resulted in:1)The infant of 4.5-18 weeks was caretaken by adult males for 7.9% of its time in early 20 weeks after birth (9.6% for males vs.5.6% for females).2)The caretaking tended towards male infants,but no differences existed among the same sex of infants.3)The intensity of caretaking increased with the rank of caretakers.4)The percent of infants caretaken time was positively related to the number of triads involved by the infant.Because the mating opportunity of males is rankdependent,results 2 and 3 imply that sexual/kin selection was involved in the evolution of male-infant caretaking (IMC) in a fuzzy way.