We propose a scheme for spread-spectrum communications using true random sequences generated by chaotic semiconductor lasers as spreading codes. These sequences can eliminate the inherent periodicity of pseudorandom sequences, enlarge the capacity of spread-spectrum codes, improve communication security, and increase the number of users of the system. When a true random sequence with an appropriate length is used as the spread-spectrum code and the information speed is maintained constant, the system acquires a greater spread-spectrum gain and a lower bit-error ratio (BER) than the traditional spread-spectrum system. The communication security is also enhanced. The BER smoothly increases with the number of users, which indicates the good multiple-access capability of the system.