This　paper　considers　multichannel　slottedALOHAfor　unicast　in　an　ad　hoc　network.　Under　a　deadline-constrained　scenario　that　a　packet　is　required　to　be　transmitted　to　an　intended　recipientwithin　a　strict　delivery　deadline　D　(in　unit　of　slot)　and　retransmission　is　not　allowed,　we　obtain　the　optimal　channel　selection　probabilities　and　the　optimal　transmission　probability　that　maximize　the　reliability.　In　particular,　the　throughput　maximization　can　be　studied　as　the　case　of　D　=　1.　Furthermore,　by　noting　that　there　is　a　tradeoff　between　reliability　and　throughput　when　D＞1,　we　obtain　the　optimal　schedule　that　maximizes　the　reliability　subject　to　a　throughput　constraint　and　the　one　that　maximizes　the　throughput　subject　to　a　reliability　constraint.