This study was designed to examine the qualities of online friendships with different gender compositions that had been maintained for varying periods of time. A total of 167 Hong Kong Internet-users rated the qualities of their same-sex and cross-sex online friendships on measures such as intimacy, trust, self-disclosure, and relational satisfaction. A 2 (gender of respondents: male vs. female) x 2 (gender of online friends: same-sex vs. opposite-sex) x 3 (duration of friendships: less than 1 year vs. 1-2 years vs. more than 2 years) factorial design was adopted. MANOVA results reveal the three-way interaction effect on intimacy, trust, and relational satisfaction. Specifically, the qualities of male-female, female-male, and female-female online friendships were generally higher for those with a longer duration than those at the early stage of friendship development. However, the qualities of male-male friendships that had been maintained for more than 2 years were lower than those maintained for 2 years or less. These findings suggest that qualities of online friendships are subject to effects of gender composition and duration. The conceptual implications of these results are discussed.