An opportunistic network is a type of challenged network that has attracted increasing attention recently. While a number of schemes have been proposed to facilitate data forwarding in opportunistic networks, an implicit assumption is made in common that each participating peer is collaborative in the network. Consequently, these schemes become vulnerable when there exist uncooperative peers in the network. In this study, we evaluate two widely used routing schemes in opportunistic networks with three types of uncooperative behaviors, namely free riders, black holes, and wormholes. Using simulation as well as realistic network scenarios, we show that the data forwarding performance degrades significantly as the number of free riders increases. Moreover, we show that the epidemic scheme is more resilient against black holes than the PROPHET scheme, while both schemes are robust against wormholes.